[pangomm] Use glibmm-2.56 instead of glibmm-2.54.

[Murray Cumming <murrayc src gnome org>]

commit 17e6b231fc5d43a3ca441da9c2c304091f5ae0e0
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Aug 25 12:04:41 2017 +0200

    Use glibmm-2.56 instead of glibmm-2.54.
    
    We have changed the ABI name in glibmm.

 configure.ac      |    6 +++---
 tools/Makefile.am |    2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 0b2deeb..663cb8d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -49,17 +49,17 @@ MM_AX_CXX_COMPILE_STDCXX([14], [noext], [mandatory])
 AC_DISABLE_STATIC
 LT_INIT([win32-dll])
 
-AC_SUBST([PANGOMM_MODULES], ['glibmm-2.54 >= 2.53.1.1 cairomm-1.16 >= 1.2.2 pangocairo >= 1.38.0'])
+AC_SUBST([PANGOMM_MODULES], ['glibmm-2.56 >= 2.55.1 cairomm-1.16 >= 1.2.2 pangocairo >= 1.38.0'])
 PKG_CHECK_MODULES([PANGOMM], [$PANGOMM_MODULES])
 
 MM_PKG_CONFIG_SUBST([GTHREAD_CFLAGS], [--cflags-only-other gthread-2.0])
-MM_PKG_CONFIG_SUBST([GMMPROC_DIR], [--variable=gmmprocdir glibmm-2.54])
+MM_PKG_CONFIG_SUBST([GMMPROC_DIR], [--variable=gmmprocdir glibmm-2.56])
 
 MM_ARG_DISABLE_DEPRECATED_API
 MM_ARG_ENABLE_DOCUMENTATION
 MM_ARG_WITH_TAGFILE_DOC([libstdc++.tag], [mm-common-libstdc++])
 MM_ARG_WITH_TAGFILE_DOC([libsigc++-3.0.tag], [sigc++-3.0])
-MM_ARG_WITH_TAGFILE_DOC([glibmm-2.54.tag], [glibmm-2.54])
+MM_ARG_WITH_TAGFILE_DOC([glibmm-2.56.tag], [glibmm-2.56])
 MM_ARG_WITH_TAGFILE_DOC([cairomm-1.16.tag], [cairomm-1.16])
 
 AC_LANG([C++])
diff --git a/tools/Makefile.am b/tools/Makefile.am
index 9d87aef..af10a4d 100644
--- a/tools/Makefile.am
+++ b/tools/Makefile.am
@@ -30,7 +30,7 @@ dist_noinst_DATA = README
 noinst_PROGRAMS  = extra_defs_gen/generate_extra_defs
 
 extra_defs_gen_generate_extra_defs_SOURCES = extra_defs_gen/generate_defs_pango.cc
-extra_defs_gen_generate_extra_defs_LDADD   = $(PANGOMM_LIBS) -lglibmm_generate_extra_defs-2.54
+extra_defs_gen_generate_extra_defs_LDADD   = $(PANGOMM_LIBS) -lglibmm_generate_extra_defs-2.56
 extra_defs_gen_generate_extra_defs_LDFLAGS = -no-undefined -avoid-version
 
 AM_CPPFLAGS = -I$(top_builddir) $(GTHREAD_CFLAGS) $(PANGOMM_CFLAGS)